The present invention generally relates to building components and, more particularly, but not exclusively, relates to building components for roofing, in the form of inflatable cushions.
Inflatable cushions comprise two or more layers of a plastics foil material such as ETFE (ethylene tetra flouro ethylene) inflated with low pressure air. The ETFE foil cushion is restrained in a perimeter frame usually manufactured from extruded aluminium, which in turn is fixed to a support structure. As the ETFE foil cushion is inflated, the ETFE is put under tension and forms a tight drum like skin. ETFE foil cushions are sold under a number of trade names, for example Texlon. ETFE cushions of this kind are fixed to a support structure to form a cladding and are used to enclose atria or other enclosed spaces to provide a transparent or translucent roof or facade to the enclosure, as an alternative to and in a similar way to glass. A number of buildings have been built using this technology most notably the Eden project in Cornwall, England.
Whenever a space is enclosed by a cladding system, due consideration needs to be given to the acoustic properties of the cladding system and how it affects the ambience of the enclosed space. ETFE foil cushions are acoustically fairly transparent having a sound reduction index of approximately 8 dBA. This is generally beneficial to the perceived acoustics of an enclosed space as the ETFE foil cushions act as acoustic absorbers to internally generated noise in that they only reflect a small proportion of the sound energy generated back into the enclosure. When it rains, however, the rain drums on the external surface of the inflated ETFE foil cushion and generates a loud noise, which can be obtrusive to the occupants.